Valve mechanism for rock drills



April 7, 1936. V R. H. SMICKLE 2,036,551

' VALVE MECHANISM FOR ROCK DRILLS Filed July 21, 1934 ig-1. J6

J3 B6 29 I INVEN T01 Ina/151151211 ck/e H1524 TTORNEY.

Patented Apr. 7, 1936 UNITED STATES PATENT OFFICE VALVE MECHANISM FOR ROCK DRILLS Application July 21, 1934, Serial No. 736,293

5 Claims.

This invention relates to rock drills, but more particularly to a valve mechanism for distributing the pressure fluid to the percussive element of a rock drill.

; V The objects of the invention are to obtain a heavy blow of the percussive element against the working implement, to utilize the pressure fluid expansively and, therefore, to reduce to a minimum the power cost of operating the drill.

Other objects will be in part obvious and in part pointed out hereinafter.

In the drawing illustrating the invention and. in which similar reference numerals refer to similar parts,

Figure 1 is a diagrammatic View, in sectional elevation, of a rock drill equipped with valve mechanism constructed in accordance with the practice of the invention and illustrating the valves and the piston in one of their limiting positions, and

Figure 2 is a view similar to Figure 1 showing the valves and the piston in their other extreme positions.

Referring more particularly to the drawing, 20 represents the cylinder of a rock drill having a free exhaust port 2| and containing a reciprocatory hammer piston 22 which controls the exhaust port 2| and carries a stem 23 to deliver blows to a working implement 24.

The cylinder 20 is shown as having an integral valve chest'25 which is bored to provide a valve chamber 26 comprising an intermediate portion 21 into which pressure fluid is introduced from supply by a passage 28. At the rear end of the portion 21 of the valve chamber are portions 29 and 30 which form continuations of the valve chamber. The portions 29 and 30 are of larger diameter than the portion 21 and of increasing diameter in the order mentioned. The portion 30 constitutes one end of the valve chamber and serves as a pressure chamber 3| which is sealed by a cover 32.

Similarly, at the forward end of the portion 21 is a portion 33 of somewhat larger diameter than the portion 21 and at the outer end of the portion .33 is a portion 34 of larger diameter and of which the outermost end serves as a pressure chamber 35. The pressure chamber 35 is normally sealed by a cover plate 36 which is secured to the valve chamber, as is the plate 32, by a bolt 31 carried in this instance by the plate 32 and extending through the valve chamber 26.

Preferably the portion 38 of the bolt 31 lying within the portion 21 of the valve chamber is of reduced diameter and the portions 39 and 40 of the bolt lying forwardly and rearwardly of the portion 38 extend through valves 4| and 42, respectively, and whereby the distribution of pressure fluid to the ends of the piston chamber 43 containing the piston 22 is effected.

The valves 4| and 42 each comprise a stem 44 guided by the portions 29 and 33, and heads 45 on the outer ends of the stems which are guided by the portions 34 and 30 of the valve chamber. The inner ends of the valves constitute pressure surfaces 46 which are constantly exposed to pressure fluid in the portion 21 of the valve chamber and cooperate with seating surfaces 41 at the junctures of the portion 27 and the portions 33 and 29 of the valve chamber to alternately close the ends of the portion 21. The outer ends of the Valves also constitute pressure surfaces, designated 48, which form inner bounding surfaces for the pressure chambers 3| ad 35.

The pressure fluid distributed by the valves 4| and 42 passes through inlet passages 49 and 59 which lead from the portions 33 and. 29 of the valve chamber at points adjacent the seating surfaces 41 to the front and rear ends, respectively, of the piston chamber 43. Leading from the piston chamber from a point intermediate the exhaust port 2| and the rear end of said chamber is a kicker passage 5| which opens into the portion 30 of the valve chamber and registers, in the open position of the valve 42, with a passage 52 in the head 45 and opening into the pressure chamber 3|.

likewise, at a point forwardly of the exhaust port 2| is a kicker passage 53 which opens into the portion 34 of the valve chamber to supply pressure fluid to a passage 54 in the valve 4| and opening into the pressure chamber 35. The passages 52 and 54 open into the peripheries of the heads 45 of the valves intermediate the ends of said heads and the peripheral portions of the heads lying outwardly of the passages 52 and 54 constitute sealing surfaces 55 which overlie the adjacent ends of the kicker passages 53 and 5| in the closed positions of the valves to prevent the escape of pressure fluid from the pressure chambers 3| and 35.

The pressure chambers 35 and 3| are provided with separate exhaust passages. The one leading from the chamber 35 is designated 56 and opens into the piston chamber 43 at a point rearwardly of the exhaust port 2| and preferably in the same transverse plane as the point of communication of the kicker passage 5| with the piston chamber. An exhaust passage 51 is provided for the pressure chamber 3| and opens into the piston chamber 43 forwardly of the exhaust port 29 and, the preferred construction, in the same transverse plane as the kicker passage 55. e

If desired, means may be provided to maintain a body of actuating fluid of nominal or 'line pressure in the pressure chambers 35 and 31! in the closed positions of the valves 4! and 32. The means illustrated comprise passages 58 leading from the supply passage 28 to points intermediate the ends of the portions 53 and 29 of the valve chamber and registering, in the closed positions of the valves, with annular grooves 59 in. the peripheries of the valve stems 54. ;Dpening into the portions 33 and 29 of the valve chambers and preferabiy adjacent the passages 58 are passages 55 which lead to the pressure chambers 35 and Si and are communicated with the passages 58 by the grcpves 55.

In order; to prevent cushioning of the yalves' 4i; and 52 during their closing movements the innermost ends of t re portions 35 and SF] of the valve chamber are vented to the atmosphere through ports iii in the valve chest.

The operation of the device is as follows: With the valves M and, 52 and the piston 22 in the positions illustrated in Figure 1 pressure fluid passes from the 'valve chamber through the inlet passage 55 into the rear end bf the piston chamber to drive the piston toward the working implement. In this position of the parts the valve ii is held against its seatfi-ll by pressure fluid in the chamber 35. This pressure fluid is entrapped in the chamber 35 by the piston 22 which Will then overlie the exhaust passage 56. The exhaust passage 5? will then be in communication with the atmosphere through the main exhaust passage 21 so that only atmospheric pressure exists in the pressure chamber 3 I. f The pressure fluid flowing over the pressure surface it holdsfthe valve 32 open during the charging of the rear end of the piston chamber 53, and in this position the valve 62 the passage 52 is in registry with the kicker passage 5!. As the piston proceeds forwardly it uncovers the passages 5i and-f 55. Pressure fluid is thus admitted throughi the kicker passage 5i and the; passage??? into the pressure chamber the valve 42 against its seat 5?.

As the valve {52 proceeds towards its seat the passage 52 moves out of registry with the passage 5i and the sealing surface 55 covers the adjacent end of the kicker passage 55 so that the pressure fluid previbusly admitted into the pressure chamber 3! is entrapped therein by the sealing surface 55 and the piston 22 which will then overlie the exhaust passage 5'1. 1

After the valve 52 has been shifted against its seat 47 the supply of pressure fluid to the rear end of the piston chamber is ciit off. ihe pressure fluid in the rear end of the piston chamber 43 thereafter acts expansively to drive the piston on its forward course until the rear end of the exhaust port 2! is uncovered by the piston. Meanwhile the valve 32 is held closed by the pressure fluid entrapped in the pressure chamber 3| and by pressure fluid flowing through the passages 58, 59, and 563 into the pressure chamber 3!. At this point in the cycle of operation the pressure fluid in the rear end of the piston chamber is exhausted to, the atmosphere, as is also that contained in the pressure chamber 35. The pressure fluid acting against the pressure surface 55 of the valve 3! then shifts said valve forwardly to open the inlet passage 49.

in the new position of the valve 4| its groove 59 is out of registry with the adjacent passage 58 so that the flow of pressure fluid from supply to the pressure chamberf35 will be out off and the pressure chamber is opened to the atmosphere through the exhaust passage 55, the rear end of the piston chamber and the main exhaust port 2! and the passage 54 will be in registry with the kicker passage 53. The pressure fluid the front end of the piston chamber will then actuate the piston 22 rearwardly;

When the piston uncovers the kicker passage 53 pressure fluid passes into the chamber 35 and the valve 58 is moved thereby to its seat 46, thus communicating the passages 58 and 68 through the groove 59 to assure full line pressure in the pressure chamber 35. Both valves will then remain closed until the front edge of the exhaust port 2| is uncovered by the piston 22 tpermit the exhaust of pressure fluid from the front end of the piston chamber to the atmosphere. At the same time the pressure fluid entrapped in the pressure chamber 3| is exhausted and the pressure fluid acting against the actuating surface 45 of the valve 52 will again shift said valve to admit pressure fluid into the rear end of the piston chamber. a?

In practice, the present invention been found to be a highly efficient device for; effecting the distribution of pressure fluid in rock drills of the hammer type. Owing to the arrangement of the various ports and passages and the manner inwhich they are; controlled by the piston and the valves the pressure fluid is used expansively for actuating the piston through a considerable portion of its stroke. The pressure fluid supply to the piston chamber may becut offat any suitable or desired point in the stroke of the piston and before the main exhaust port 2| is uncovered. In; consequence, an efficient drilling actionmay be obtained with a minimum consumption of pressure fluid since, as may be readily observed, no pressure fluid is exhausted to the atmosphere without first performing useful work. I claim: 7 g j 1- Ina fluid actuated rock drill, the combination of a cylinder and a piston, an exhaust porttrapped pressure fluid from the valve chambers to the cylinder and being controlledby the piston;

2. In a fluid actuated rock drill, the combination of a cylinder and a piston; an exhaust port in the cylinder controlled by the piston, a valve chamber, inlet passages leading from the valve chamber to the ends of the cylinder, valves in the valve chamber for controlling the inlet passages, said valves being constantly exposed at one end to pressure fluid for actuating them in one direction, kicker passages for conveying pressure fluid from the cylinder to the valve chamber and being controlled by the piston and the valves, passages in the valves to register with the, kicker passages for supplying. pressure fluid to the ends of the valve'chamber r'or actuating the valves in the opposite direction, and exhaust passages for conveying pressure fluid from the ends of the valve chamber to the cylinder and being controlled by the piston.

3. In a fluid actuated rock drill, the combination of a cylinder and a piston, an exhaust port in the cylinder controlled by the piston, a valve chamber, inlet passages leading from the valve chamber to the ends of the cylinder, valves in the valve chamber for controlling the inlet passages, differential actuating surfaces on the valves of which the surfaces of smaller area are constantly exposed to pressure fluid for actuating the valves in one direction, kicker passages for supplying pressure fluid from the cylinder to the actuating surfaces of larger area for throwing the valves in the opposite direction and being controlled by the piston and the valves, and exhaust passages for conveying the pressure fluid from the actuating surfaces of larger area to the cylinder and being controlled by the piston.

4. In a fluid actuated rock drill, the combination of a cylinder and a piston, an exhaust port in the cylinder controlled by the piston, a valve chamber, inlet passages leading from the valve chamber to the ends of the cylinder, valves in the Valve chamber for controlling the inlet passages, difierential actuating surfaces on the valves of which the surfaces of smaller area are constantly exposed to pressure fluid for actuating the valves in one direction, kicker passages for supplying pressure fluid from the cylinder to the actuating surfaces of larger area for throwing the valves in the opposite direction and being controlled by the piston and the valves, passages for conveying pressure fluid from supply to the actuating surfaces of a larger area for holding the valves in a limiting position and being controlled by the valves, and exhaust passages for conveying the pressure fluid from the larger actuating surfaces to the cylinder and being controlled by the piston.

5. In a fluid actuated rock drill, the combination of a cylinder and a piston, an exhaust port in the cylinder controlled by the piston, a valve chamber, front and rear inlet passages leading from the valve chamber to the corresponding ends of the cylinder, valves in the valve chamber to control the inlet passages and having differential pressure surfaces of which the surfaces of smaller area are constantly exposed to pressure fluid for shifting the valves to open the inlet passages, kicker passages leading from points forwardly and rearwardly of the exhaust port to corresponding points in the valve chamber to supply pressure fluid to the actuating surfaces of larger area for actuating the valves to and holding them in closed positions, said kicker passages being controlled by the piston and the valves, and crossed exhaust passages for conveying the holding pressure fluid to the cylinder and being controlled by the piston.

RAYMOND H. SIVIICKLE. 

